Ninety percent of patients (64 of 71) underwent extended thymectomy at the time of primary pleural surgery (recurrence rate: 49.0%). Six patients had thymomectomy only (50% recurrences). Only 20.6% of patients undergoing extended thymectomy at primary pleural surgery had MG. Thus, general practice among thymic surgeons in primary surgery of TETs with pleural involvement is to add extended thymectomy. No conclusions on the value of added basic or extended thymectomy to thymomectomy at primary surgery for pleural disease of TETs for FFR can be drawn from this study.